Selective extraction of oxygenated terpene in caraway (Carum carvi L.) using subcritical water extraction (SWE) technique

Caraway contains terpenes such as carvone, limonene and carveol, that have antibacterial and antifungal properties. Subcritical-water extraction (SWE) can be used to extract terpenes by changing temperature under high pressure. This study evaluated the SWE of terpenes from caraway when varying the extraction conditions of temperature (110 °C–190 °C), time (5–15 min), and particle size (>1000, 850–1000, 425–850, and < 425 μm). The optimal conditions for the extraction of carvone, which determines the quality of caraway, were found to be 170 °C, 15 min, and a particle size of < 425 μm. Also, the carvone yield was much higher when using SWE (28.5 mg/g caraway) than for solvent extraction (20.2 mg/g caraway) and hydrodistillation (19.8 mg/g caraway). The overall results showed that oxygenated terpene like carvone has a high solubility in subcritical water, and nonoxygenated terpene like limonene can partially be converted to carvone via a process of SWE.